Does cochlear reimplantation affect speech recognition?

Although cochlear implantation has been proven to be a very effective method of rehabilitation for post-lingually deaf adults and pre-lingually deaf children, as electronic devices, cochlear implants are occasionally subject to damage or breakdowns. In these cases, reimplantation would be necessary. The aim of this study was to find out whether or not there are any negative effects on speech abilities after reimplantation with the same type of multichannel digital implant in the same ear. Seven patients were provided with a digital multi-channel cochlear implant. One subject suffered manipulative damage to the implant, and in six subjects an implant failure was observed. All reimplantations were performed on the same ear as the initial implantation. with the same implant type. Parameters such as insertion depth and number of active channels were the same in all subjects before and after reimplantation. Immediately following the revision surgery, three patients attained the same level of hearing that they had with their original implants. Three months following reimplantation, five subjects achieved almost the same scores that they had before reimplantation. The results showed that cochlear implant patients undergoing re-implantation can anticipate achieving nearly the same level of speech recognition as they had with their original implant. Nevertheless, patients need to be aware of potential problems before undergoing reimplantation so that expectations are not too high.     

How does cochlear implantation affect the contralateral vestibular system?

Cochlear implantation has been performed for 16 years by investigators at Semmelweis University. During this period, different types of cochlear implants have been used and, in 30% of cases, hearing was observed to be restored in the nonimplanted ear. In addition to contralateral hearing improvement, significant improvement was observed in the caloric responsiveness of the nonoperated labyrinth. The preoperative median value of the average slow-phase velocity of the caloric test increased, and the increase was statistically significant on the contralateral side. The reason for this caloric response improvement is unclear, although possible explanations are brain plasticity or presently obscure trophic influence on the vestibular system. Whereas the role of brainstem function in the improvement of the contralateral ear's caloric response remains unclear it is also possible that hearing impulses affect the labyrinth. Clearly, the influence of cochlear implants on vestibular function requires further investigation to explain the improvement of contralateral vestibular responsiveness.     

Does size of the cochlear nerve affect postoperative auditory performance in pediatric cochlear implant patients with normal cochlear nerves?

IntroductionCochlear implantation is an effective treatment method for severe to profound hearing loss. Many factors that may influence cochlear implantation success have been explained in previous studies. Apart from those, minor differences in size of normal cochlear nerves may affect postoperative performance.ObjectiveTo investigate whether the minor differences in cochlear nerve size in normal cochlear nerves affect postoperative cochlear implant performance.Methods30 pediatric prelingually deaf patients who were treated with cochlear implantation were included in this study. From the reconstructed parasagittal magnetic resonance images, the diameter and cross-sectional area of the cochlear nerve on the ipsilateral and contralateral side were measured. Auditory evaluations were performed 1, 3, 6 and 12 months following the first fitting. All the analysis was performed by using EARS®, evaluation of auditory responses to speech tool. Correlation between cochlear nerve diameter, cross-sectional area and postoperative auditory perception was analyzed to determine whether variation in cochlear nerve size contributes to postoperative auditory performance.ResultsThe mean diameter of the cochlear nerve on the ipsilateral side was 718.4 μm (504.5 ? 904.3 μm) and mean cross sectional area was 0.015 cm² (0.012 ? 0.018 cm²). On the contralateral side the mean cochlear nerve diameter was 714.4 μm (502.6 ? 951.4 μm) and mean cross sectional area was 0.014 cm² (0.011 ? 0.019 cm²). The correlation between the diameter and cross-sectional area of the ipsilateral and contralateral cochlear nerve revealed no significance. Mean score at first month monosyllable-trochee-polysyllable test, MTP1, was 0.17 (0.08 ? 0.33), at 6th month with 6 words test, 6th month MTP6 was 0.72 (0.39 ? 1.0), at 6th month with 12 words, 6th month MTP 12 was 0.46 (0.17 ? 0.75) and at 12th month with 12 words, 12th month MTP12 was 0.73 (0.25 ? 1.0). There was no correlation between the monosyllable-trochee-polysyllable test, values at any time with the diameter of the ipsilateral cochlear nerve. However, the first month MTP, 6th month MTP6 and 12th month MTP12 correlated with the cross-sectional area of the ipsilateral cochlear nerve.ConclusionMeasuring the cross sectional area of the normal- appearing cochlear nerve may give important prognostic knowledge on cochlear implant outcomes. In patients with a larger cross sectional area the auditory performance was better and faster. Although normal appearing, slight differences on cross sectional area of the cochlear nerve may affect performance. Measuring the size of the cochlear nerve on parasagittal magnetic resonance images may provide beneficial information on the postoperative rehabilitation process.     

Does music perception have an impact on quality of life following cochlear implantation?

CONCLUSION: Despite the decrease in listening habits, about half of the patients still enjoy music post implantation. Better quality of sound through the implant improves music enjoyment and contributes to achievement of better postoperative quality of life (QOL). OBJECTIVES: To evaluate music perception and enjoyment in cochlear implant (CI) users, and to assess their influence on QOL. MATERIALS AND METHODS: Sixty-five post-lingually deaf CI recipients were enrolled in this study. A musical questionnaire evaluated musical background, listening habits, and quality of musical sound through the CI. The validated Glasgow Benefit Inventory (GBI) was used to quantify changes in QOL. RESULTS: Fifty-two patients answered the questionnaires. Listening habits (music enjoyment and hours spent listening to music per week) significantly decreased following implantation when compared with the same parameters before deafness. Nevertheless, 52% of the patients enjoyed music post implantation. The quality of musical sound was rated >50 (0-100 scale) for the adjective pairs 'like-dislike', 'sounds like music-doesn't sound like music' and 'natural-mechanical' by most users. Med-el device users obtained better scores in the adjective pair 'sounds like music-doesn't sound like music' than Cochlear device users. Recipients rating higher scores for quality of sound enjoyed music post implantation and had higher total GBI scores than those rating lower scores.     

Does music perception have an impact on quality of life following cochlear implantation?

Conclusion. Despite the decrease in listening habits, about half of the patients still enjoy music post implantation. Better quality of sound through the implant improves music enjoyment and contributes to achievement of better postoperative quality of life (QOL). Objectives. To evaluate music perception and enjoyment in cochlear implant (CI) users, and to assess their influence on QOL. Materials and methods. Sixty-five post-lingually deaf CI recipients were enrolled in this study. A musical questionnaire evaluated musical background, listening habits, and quality of musical sound through the CI. The validated Glasgow Benefit Inventory (GBI) was used to quantify changes in QOL. Results. Fifty-two patients answered the questionnaires. Listening habits (music enjoyment and hours spent listening to music per week) significantly decreased following implantation when compared with the same parameters before deafness. Nevertheless, 52% of the patients enjoyed music post implantation. The quality of musical sound was rated >50 (0–100 scale) for the adjective pairs ‘like-dislike’, ‘sounds like music-doesn't sound like music’ and ‘natural-mechanical’ by most users. Med-el device users obtained better scores in the adjective pair ‘sounds like music-doesn't sound like music’ than Cochlear device users. Recipients rating higher scores for quality of sound enjoyed music post implantation and had higher total GBI scores than those rating lower scores.     

Basic flbroblast growth factor protects auditory neurons and hair cells from noise exposure and glutamate neurotoxicity

The purpose of the present study was to determine protectivie effects of basic fibroblast growth factor (bFGF) on cochlear neurons and hair cells in vitro and in vivo. In experiment I, cultured spiral ganglion neurons (SGNs) prepared from P3 mice were exposed to 20mM glutamate for 2 hours before the culture medium was replaced with fresh medium containing 0, 25, 50, and 100 ng/ml bFGF, respectively. Fourteen days later, all cultures were fixed with 4% paraformaldehyde, and stained with 1% toluidine blue. The number of surviving SGNs were counted and the length of SGNs neurites were measured. Exposure to 20 mM glutamate for 24 hours resulted in an inhibition on neurite outgrowth of SGNs and elevated cell death. Treatment of the cultures with bFGF led to promotion of neurite outgrowth and elevated number of surviving SGNs. Effects of bFGF were dose dependent with the highest potency at 100 ng/ml. In experiment II, in vivo studies were carried out with guinea pigs in which bFGF or artificial perilymph was     

Basic fibroblast growth factor protects auditory neurons and hair cells from noise exposure and glutamate neurotoxicity

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Comparison of two cochlear implantation techniques and their effects on the preservation of residual hearing. Is the surgical approach of any importance?

The goal of this work was to review the pre-and postsurgical auditory thresholds of two surgical implantation techniques, namely the mastoidectomy with posterior tympanotomy approach (MPTA) and suprameatal approach (SMA), to determine whether there is a difference in the degree of preservation of residual hearing. In a series of 430 consecutive implanted patients 227 patients had measurable pre-operative hearing thresholds at 250, 500, and 1,000 Hz. These patients were divided into two groups according to the surgical technique that was used for implantation. The SMA approach was followed for 84 patients in Amsterdam, whereas the MPTA technique was adhered to 143 patients in Maastricht. The outcome variables of interest were alteration of pre-and postoperative auditory thresholds after cochlear implantation. Complete or partial preservation of residual hearing was obtained in 21.4 and 21.7 % in the SMA and MPTA group, respectively. No statistical differences could be found between the SMA and MPTA group (p = 0.96; Chi-square test). The SMA technique is correlated with a similar degree of hearing loss after cochlear implantation compared to the MPTA technique. However, both techniques were not able to conserve a measurable amount of hearing in patients with a substantial degree of residual hearing. Therefore, both surgical techniques need to be refined for patients in which residual acoustical hearing is pursued.     

Does cochlear implantation improve speech recognition in children with auditory neuropathy spectrum disorder? A systematic review

Abstract

Objective: Cochlear implantation (CI) is a standard treatment for severe-profound sensorineural hearing loss (SNHL). However, consensus has yet to be reached on its effectiveness for hearing loss caused by auditory neuropathy spectrum disorder (ANSD). This review aims to summarize and synthesize current evidence of the effectiveness of CI in improving speech recognition in children with ANSD. Design: Systematic review. Study sample: A total of 27 studies from an initial selection of 237. Results: All selected studies were observational in design, including case studies, cohort studies, and comparisons between children with ANSD and SNHL. Most children with ANSD achieved open-set speech recognition with their CI. Speech recognition ability was found to be equivalent in CI users (who previously performed poorly with hearing aids) and hearing-aid users. Outcomes following CI generally appeared similar in children with ANSD and SNHL. Assessment of study quality, however, suggested substantial methodological concerns, particularly in relation to issues of bias and confounding, limiting the robustness of any conclusions around effectiveness. Conclusions: Currently available evidence is compatible with favourable outcomes from CI in children with ANSD. However, this evidence is weak. Stronger evidence is needed to support cost-effective clinical policy and practice in this area.     

How can the cochlear amplifier be realized by the outer hair cells which have nothing to push against?

D-Methionine has recently been advocated as a protectant against cisplatin toxicity. The use of systemic D-methionine as a protector was studied in 58 guinea pigs. Kinetics and distribution of [11CH(3)]D-methionine was analysed by positron emission tomography. Cisplatin and the monohydrated complex of cisplatin was quantified in blood ultrafiltrate using reversed-phase liquid chromatography with post-column derivatisation. Administration of 300 mg/kg of D-methionine caused a 30% decrease in the area under the concentration-time curve (AUC) of cisplatin. The toxic effect of cisplatin was studied after dose adjustment of cisplatin, i.e. with similar cisplatin AUC in the group receiving D-methionine and the saline control group. A significant ototoxic effect, measured as difference in pre- and 96 h post-treatment electrophysiological hearing threshold (auditory brainstem response), was observed at stimulus frequencies of 30 and 20 kHz. There was no difference between the groups in the extent of threshold shift. Quantitative outer hair cell counts showed a similar loss of cells in the two groups. All animals had a significant increase in plasma-creatinine but there was no difference between the groups. The results indicate that protection from cisplatin ototoxicity by systemic D-methionine can be explained by a lowered systemic exposure to the drug.     

Parental and program's decision making in paediatric simultaneous bilateral cochlear implantation: Who says no and why?

Objective

To evaluate initial candidacy for bilateral simultaneous cochlear implantation in children.

Design

Prospective case series.

Setting

Tertiary academic pediatric hospital.

Participants

As part of our research protocol all children eligible for cochlear implantation were assessed for suitability to receive a simultaneous bilateral implant. Over a 12-month period (January to December 2007) 78 children received a total of 95 cochlear implants. Children with sequential second implants (24), revision cases (4), and out of province recipients (4) were excluded. The remaining 46 patients were assessed for bilateral simultaneous implantation.

Main outcome measures

Team/parental decision to proceed with bilateral simultaneous implantation.

Results

17 children (37%) received simultaneous bilateral implants. 29 children (63%) were not considered suitable for simultaneous bilateral implantation. Reasons included developmental delay (10), residual borderline hearing in the second ear (9), parental/patient refusal (6), abnormally poor speech development for age (2), and abnormal cochlear anatomy precluding implantation (2). None were considered unsuitable for the more prolonged operative procedure on medical grounds.

Conclusions

Although bilateral implantation is thought to produce the optimal auditory outcome, not all patients are suitable, nor do all parents wish to proceed, when assessed for simultaneous implantation. Some of these patients are likely to be candidates for sequential bilateral implantation in due course.     

An "endosteal electrode" for cochlear implantation in cases with residual hearing? Feasibility study: preliminary temporal bone experiments.

BACKGROUND: Over the years, an increasing number of patients with some degree of residual hearing have received cochlear implants. In these cases, the marginal benefit provided by hearing aids alone is not sufficient; however, as experience has already shown, when hearing aids are used in combination with a cochlear implant, more benefit may be obtained. As a prerequisite, this requires that residual hair cell function must remain intact postoperatively. One of the European pioneers of cochlear implants, Ernst Lehnhardt, questioned whether residual hearing might better be preserved if the implanted electrode permits the fluid-filled inner ear space to remain intact. Subsequently, he proposed insertion of a very flat electrode array design into the extraluminal space between the spiral ligament and the bony cochlear wall (endosteum). OBJECTIVE: Our study aimed to determine whether it is feasible to insert an endosteal electrode model intracochlearly but extraluminarily, anatomically, and ultimately surgically and to determine the impact on surrounding intracochlear structures. METHODS: Insertion of two silicon models of an endosteal electrode were carried out in 15 human temporal bones. Histologic examination of the temporal bones after electrode insertion was performed on both fresh and fixed specimens to determine whether the desired anatomic site of insertion was achieved. In combination with light reflected and electron microscopic techniques, the extent to which the surrounding structures were impacted was also examined. RESULTS: Successful insertion of the prototype silicon endosteal electrodes was performed intracochlearly and extraluminarly in 11 of the 15 temporal bone specimens, confirming the anatomic feasibility of insertion into the crevice between the spiral ligament and endosteum. CONCLUSIONS: On the basis of the anatomy of the human temporal bone, insertion of an "endosteal electrode" is feasible. Subsequently, in vivo animal studies are needed to determine the physical effects of insertion of an endosteal electrode design prototype upon the functionality of the surrounding intracochlear structures and in particularly the ability to preserve hearing function.     

Combining perimodiolar electrode placement and atraumatic insertion properties in cochlear implantation -- fact or fantasy?

CONCLUSIONS: Except for basal cochlear traumatization, all specimens implanted into scala tympani showed atraumatic insertion properties and good perimodiolar electrode positioning. Cochleostomy preparation and placement can have a significant impact on levels of basal cochlear trauma. OBJECTIVE: In the past, perimodiolar cochlear implant electrodes increased the risk for intracochlear traumatization when compared to free-fitting arrays. Recently, however, clinical evidence for atraumatic perimodiolar implantations with preservation of residual hearing has been described. The aim of this paper was to histologically evaluate a perimodiolar cochlear implant array for its insertion properties in cadaver human temporal bones. Surgical and electrode factors, as well as preparation artifacts influencing intracochlear trauma, were considered in the evaluation. MATERIALS AND METHODS: Sixteen human temporal bones were harvested up to 24 hours post mortem and implanted immediately with the Nucleus 24 Contour Advance cochlear implant electrode array. Implantations were either performed using a regular caudal approach cochleostomy or through the round window membrane. After implantation, all bones underwent special histological processing, which allowed sectioning of undecalcified bone. Insertion properties were evaluated according to a grading system. RESULTS: Fourteen specimens were implanted into scala tympani and only two exhibited basal trauma attributable to electrode insertion characteristics. Two bones were implanted into scala vestibuli after causing trauma in the region of the cochleostomy. Insertion depths ranged from 180 degrees to 400 degrees. All bones showed good perimodiolar electrode positioning. Basal trauma due to surgical issues and histological artifacts was present in 10 of 16 bones.     

Chemical labyrinthectomy and cochlear implantation for Menière's disease--an effective treatment or a last resort?

The surgical management of Menière's disease presents a difficult and controversial problem and includes various procedures ranging from 'placebo operations' to vestibular nerve section. The situation is even more complex in the case where the only hearing ear is affected. We present a case of severe debilitating vertigo due to Menière's disease that was treated by chemical labyrinthectomy and cochlear implantation. This unique management strategy allowed restoration of useful hearing and relief of vertigo.